President Barack Obama has called Martin Luther King Jr. his North Star — a standard of “bold leadership and prophetic eloquence.” During the 2008 campaign, he said he would never have gotten as far were it not for the civil rights movement. “I stand on the shoulders of giants,” he said in a speech in Selma, Ala.

But when it comes to many of the aging leaders who marched with King, the relationship is more complicated. Obama, for the most part, has kept the civil rights movement’s old guard at arm’s length. They, in turn, are wary, their sense that the election of the first black president represented the ultimate success of the movement now tinged with disappointment that Obama has not more aggressively confronted issues of economic inequality.

“Treat him as you would any other president — none in my lifetime has totally satisfied me,” said Julian Bond, the longtime activist and former chairman of the NAACP who once was a student of King’s at Morehouse College.

This ambivalence will be one of the undercurrents Sunday when Obama leads the tributes to King at the dedication of a memorial to the slain civil rights leader on the National Mall — a ceremony that was postponed from August because of Hurricane Irene — and at a private gathering of King family members and civil rights leaders that the president will host at the White House afterward.

With thousands of people expected for the dedication and the president scheduled to speak on King’s legacy, it will be Obama’s most public embrace of the movement his predecessors in the White House have celebrated but usually kept at a distance.

“I don’t really think any president has fully brought movement leaders into the inner circle, and to expect that Obama, as a black president, ought to be closer than others have been, I think, is not a fair expectation,” said Scott Sandage, a cultural historian at Carnegie Mellon University.

“The truth is, there is really no president who has chummed up with the civil rights movement. For a lot of reasons, presidents hold movement leaders at arm’s length, going back to FDR, JFK and Eisenhower — all of them were pressed by the movement to move faster on civil rights.”

For Obama, who was 6 years old when King was killed in Memphis on April 4, 1968, the distance underscores a generational divide, the burden of heightened expectations he contends with, and the difference between activism and political leadership — one involving marching with a list of demands, the other hammering out compromise.

Obama keeps a bust of King in the Oval Office, and just outside that historic room, he recently installed “The Problem We All Live With,” the iconic Norman Rockwell painting that depicts then 6-year-old Ruby Bridges, integrating New Orleans schools in 1960.

But leaders of the movement can be more problematic.

Jesse Jackson, for example, has had an up-and-down relationship with Obama. Always controversial, he supported Obama in 2008, but the two fell out after Jackson was overheard on a hot microphone complaining, among other things, that Obama was “talking down to black people.”

Jackson apologized and was later photographed weeping with emotion when Obama won the presidency. But he has an infrequent presence around the White House; records show his last visit was in 2009.

“We have a range of relationships with him among civil rights leaders,” the Rev. Jesse Jackson said of Obama, adding: “I don’t know any who didn’t vote for him, and who do not expect to endorse him again.”

Along with other former lieutenants of the movement such as the Rev. Joseph Lowery and former Atlanta Mayor Andrew Young, Jackson will be on hand for Sunday’s dedication, which originally was scheduled for the 48th anniversary of King’s “I Have a Dream” speech.

Young, who supported Hillary Clinton in 2008 after knowing her for many years, said he doesn’t have a personal relationship with Obama, “But that is OK.”

“I had a hard time supporting Obama because I was very close to Hillary Clinton,” Young said. “I wasn’t a true believer, and I was convinced people were setting him up to do exactly what they did: blame him for all the troubles of the past then try to get rid of him.”

Young gives Obama credit for stabilizing the financial sector, expanding health care to young adults and for being a “sensitive and responsive world leader.” He said he “empathizes, tremendously” with Obama’s travails in office but hasn’t given advice, because he hasn’t been asked.

“Is he what I expected? Almost,” Young said. “He is very well-respected in most of the world. He is smart and he works hard — he is amazingly humble. I don’t think we can do any better.”

In his 2007 Selma speech, Obama called himself part of the “Joshua generation” of activists, inheritors of the duties handed down by Lowery, Jackson, Young, Rep. John Lewis (D-Ga.) and others who knew and worked alongside King.

But the president’s political mettle was not forged in their fires. His ascent was not beholden to old style, civil rights activism; and his politics of race-neutral pragmatism has at times frustrated some of the leaders.

“Jackson, Young, [Al] Sharpton and going further back into history — they were confronters,” said Sandage of Carnegie Mellon. “They are just about to unveil a monument to King that has him standing shoulders back and arms folded, the ultimate body language of in-your-faceness. Could anything be further from Obama’s style?”

Bond said there is a role for civil rights leaders to “vigorously challenge what you believe are [Obama’s] mistakes or missteps.” He has a cordial, if distant relationship with the White House and splits the difference with Obama, saying the president should fight harder and explain himself better. But Bond gives Obama strong marks for his achievements, including health care reform.

“I never imagined he would face the level of opposition he faces from the Republican Party,” Bond said. “He is not as liberal as I had hoped he would be, but that may be my misunderstanding of who he was and what he was prepared to do.”

The top concern of civil rights leaders is jobs. When Obama stands Sunday before the 30-foot granite statue of King — “the Stone of Hope, cut from the Mountain of Despair,” organizers call it, borrowing a line from King — unemployment among African-Americans will stand at 16 percent, nearly double the national rate of 9.1 percent.

It’s a tricky moment for the president, in part because King, whom he stands to honor, made a priority of addressing black poverty and economic disempowerment.

“There is a tremendous amount of continued support and affinity with the president’s policies and efforts to lead the nation,” said Marc Morial, president of the National Urban League and more a member of Obama’s “Joshua” generation than Jackson’s “Moses” generation. “But I think a continued concern that I have expressed, probably more vocally than anyone, is about jobs and the economy and the continued deterioration of economic conditions in urban areas and for African Americans.”

In June, the president took a break from debt ceiling negotiations to meet at the White House with Morial and Benjamin Jealous, the current president of the NAACP. The president’s gesture was intended to show regard for the two leaders and their issue — a plan for easing unemployment in urban areas. He received their proposal privately, without public comment, and hasn’t mentioned it since.

Sharpton, younger than the other leaders and a product of New York, not the South, has become a frequent defender of the president as the host of his own show on MSNBC, and seems to have Obama’s ear more than the rest. The two consult on education and economics, among other issues. Sharpton recently described it as “open access” and said he made an agreement with Obama that “we would always talk.”

“He and I don’t agree on everything,” Sharpton said. “But I always want to be able to work with him. If I am out there calling the president names, I may win some applause, but we are not going to win any bills.”

Still, civil rights is a thread that runs through the administration, sometimes out of public view. Obama in 2010 hosted an intergenerational reflection on civil rights at the White House coinciding with King’s annual holiday. The group he gathered talked about the movement and viewed the Emancipation Proclamation on display in the Oval Office.

“Ms. Harvey just now was whispering in my ear, as you guys were walking in, that this must be the Lord’s doing, because we’ve come a mighty long way,” Obama said at the time, referring to 102-year-old Mabel Harvey, one of his visitors.

Four months later, Obama delivered the eulogy for another of the intergenerational talk participants, longtime civil rights activist Dorothy Height, whom he hailed as “Queen Esther to this Moses generation.”

Obama, who wiped away tears at the service, recalled Height’s 21 visits to the White House. “We came to love her stories. And we loved her smile. And we loved those hats that she wore like a crown. Regal,” he said.

Height was to have attended a meeting last year at the White House with Morial, Sharpton and Jealous to talk about jobs and the economy. The other three made the meeting with Obama and later appeared outside, in a blizzard, to talk with reporters.

Obama in April met privately with the eight surviving members of the 1968 Memphis sanitation strike, an epochal event in the movement that led to improved work conditions and historic recognition of the workers’ union. During his summer vacation, he played golf on Martha’s Vineyard with Vernon Jordan, a longtime activist and former president of the Urban League-turned Washington corporate power broker.

Less visible these days is Lowery, a key player from the 1960s who delivered the benediction at Obama’s Inauguration, including passages from “Lift Every Voice and Sing,” also known as the black national anthem. Lowery recently turned 90 years old.

In February, Obama awarded Lewis, whose skull was shattered in the Selma march in 1965, the Presidential Medal of Freedom. As he sat there during the White House ceremony, Lewis later recalled, “I just kept thinking, I wish Dr. King were here.”